ased on the EJB Query Language (EJB QL) first introduced in EJB 2.0, the Java Persistence Query Language (JPQL), is a portable query language designed to
combine the syntax and simple query semantics of SQL with the expressiveness
...

A popular language called Java Persistence Query Language (JPQL) is used for
that purpose. 6.2.5.2 Use Java Persistence Query Language Statement The Java Persistence Query Language (JPQL) is a platform-independent object ...

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Java Persistence Query Language(JPQL) is defined by the Java Persistence API(JPA) and it is very easy to use for querying database with entities. But sometime it becomes pretty hard to find similar function in JPQL which is available only in a particular database.

Introduction
Overview
The
Java Persistence API (JPA) is the Java standard for mapping Java
objects to a relational database. Even though proprietary mapping
products like Hibernate and TopLink still exist, they are now focused on
providing their functionality through the JPA API, allowing all
applications to be portable across JPA implementations.

The Java Persistence Query Language defines queries for entities and their persistent state. The query language allows you to write portable queries that work regardless of the underlying data store. The EntityManager.createQuery and EntityManager.createNamedQuery methods are used to query the data-store by using Java Persistence Query Language queries.........................................................................................................................................................what is jpa, what is jpql, Java Persistence Query Language, java, jpa named queries, jpa query methods. java ee, tutorial, example

JPA specification does not support changing the transaction isolation level and that is the reason HibernateExtendedJpaDialect and IsolationSupportSessionTransactionData classes have been developed in the wild (Disclaimer: I am merely copying and pasting the ones I found below but all credits go their original authors).
We went ahead and tried HibernateExtendedJpaDialect just to notice that randomly entity persistence would fail with:
WARN [org.